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Avalanche Forecast

Archived

Dec 17th, 2025–Dec 20th, 2025

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Waterton Lakes, Waterton.

Stormy weather continues through the weekend with lower freezing levels. Careful travel and snowpack assessment will be required, as conditions vary drastically by elevation band. Below treeline will still be very thin with early season hazards like stumps logs and rocks.

Confidence

Moderate

  • Uncertainty is due to limitations in the field data.

Avalanche Summary

No new avalanches observed however limited observations since Wednesday.

Snowpack Summary

Up to 40cm of new snow has been redistributed by strong to extreme winds in the alpine and at treeline. This sits atop a new crust from this weeks warm weather and rain. Our midpack is 80-100cm of refreezing snow. At 1700 m and above, the base of the snowpack consists of a series of crusts and facets to the ground. Below 1700 m the snowpack still very thin and some areas will only have this most recent storm snow on ground.

Weather Summary

Thurs

Snow begins in the afternoon up to 10cm overnight. Alpine high -5°C with strong to extreme SW winds.

Fri

Snow continues through the day 5cm. Alpine high -5°C with winds decreasing to moderate SW

Sat

Snow through the day 5cm. Alpine high -5°C with moderate SW winds.

For current weather forecast, please see Mountain Weather Forecast

Current ECC weather table can be found Here

Terrain and Travel Advice

  • Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.